Wydział Chemii

Vera I. Tsaryuk

V. F. Zolin

L. Puntus

V. Savchenko

Janina Legendziewicz

Jerzy Sokolnicki

Roman Szostak

2000

Journal of Alloys and Compounds

300-301

184-192

10.1016/S0925-8388(99)00720-3

Naukowa

Angielski

Artykuł

Luminescence and excitation of luminescence vibronic spectra as well as IR and Raman spectra of europium nitrates with 1,10-phenanthroline derivatives of formula Eu(NO₃)₃.Ph₂ were studied. The effect of size of ligands and their effective charges on crystal structure and, as a consequence, on spectroscopic characteristics was investigated under conditions where one type of ligand (NO₃⁻ group) is sufficiently rigid. The second ligand, heterocyclic diimine, can change its size and donor-acceptor properties when the substituents are varied. Stark splittings and relative intensities of the Eu³⁺ electronic transitions, the behaviour of vibration frequencies, and vibronic interaction were studied. It was demonstrated that nitrates under investigation have identical composition but form two different structural groups with small and bulky phenanthroline derivatives due to the influence of steric factor. All nitrate anions in the compounds are coordinated and the Eu-O (NO₃⁻) bonds are relatively strong. The values of the splitting of stretching vibrations of the NO₃⁻-anions (▵=ν₄−ν₁) and position of the band of ν(Eu–O) vibration show that the strongest Eu–O bonds are formed in Eu(NO₃)₃.Nphen₂, Eu(NO₃)₃.Tmphen₂ and Eu(NO₃)₃.Dphphen₂ due to high acceptor properties of nitro-phenanthroline and large size of tetramethyl- and diphenyl-phenanthroline molecules. Weak vibronic mixing of electronic and vibronic states was demonstrated in the region of ⁵D₀–⁷F₂ transition of Eu³⁺. The vibronic satellites of ⁵D₀–⁷F₀ -transition due to vibrations of the NO₃⁻-group borrow about 1–2% of the intensity of the electric-dipole ⁵D₀–⁷F₂ transition yielding the increase of their relative intensity of 100 times in the Stokes sideband.

Crystal and ligand fields, Electron-phonon interaction, Luminescence

https://doi.org/10.1016/S0925-8388(99)00720-3

http://www.elsevier.com